Tear fluid provides a viable source of biological analytes that can indicate various health states of an individual from which tear fluid is generated. However, collection of tear samples for testing is difficult. Many processes for collecting tear samples usually irritate the eye and produce tear fluid having constituents which can lead to erroneous test results. For example, tear fluid generated from irritation of an eye, such as touching of the eye and tear fluid generated from an emotional reaction comprise different constituents than basal tears and are generally produced in greater quantity than basal tears. Such reflex and emotional tears interfere with composition of tear samples of interest.
In order to avoid some of the aforementioned drawbacks associated with collection of tear fluid, contact lenses have been established that employ internal sensing platforms for in-situ testing of tear fluid for analytes. These contact lenses generally test tear fluid that forms a tear film over the contact lens. However, the total volume of tear fluid establishing the tear film is often insufficient for in-situ testing of various analytes.